Bleach activators

ABSTRACT

A bleach composition comprises a peroxygen bleach source (for instance hydrogen peroxide, a perborate or a percarbonate salt) and an activator of the formula I: ##STR1## in which X is O or S; one of E and G is --A-- and the other is --N(R 2 )--; 
     A is --O-- or --S--; 
     R 1  is a C 1-50  alkylene group (including cyclo alkylene), optionally interrupted by an arylene group and/or by one or more ether, ester, anhydride, thioether, secondary or tertiary amine, amide or imide linkage, an arylene group or an alkarylene group; 
     R 2 , is selected from H, alkyl, aralkyl, alkaryl and aryl; 
     R 3  is alkyl, aralkyl, alkaryl or aryl, or, when E is --N(R 2 )--, H; 
     in which R 2  and R 3  can be joined so as to form a heterocyclic ring with the atoms to which they are attached, and/or in which R 1  can be joined with R 2  or R 3  ; and 
     L is a leaving group which may optionally be joined to any of R 1 , R 2  and R 3 . The activator gives the composition good bleaching at low temperatures, minimal dye and fabric damage and which bleach a wide range of oxidisable stains.

This application is a 371 of PCT 16895/01847 filed Aug. 3, 1995.

The present invention relates to activators for use in conjunction withperoxygen bleaches to improve low temperature bleaching, in particularlaundry detergent compositions, textile bleaches, hard surface cleaners,pulp bleaching and other bleaching environments. The activator compoundscontain carbamate groups.

In EP-A-0,170,386, peroxy acid bleaching compounds include in theperacid molecule an amide group. The peracids may be generated in situby the reaction between an activator, that is a compound in which theperhydroxyl group of the percarboxylic acid is replaced by a leavinggroup, and a peroxygen source, such as an inorganic persalt. Theactivator and persalt may be incorporated into the same detergentcomposition together with other components. Alternatively, stablemagnesium salts of the percarboxylic acid may be incorporated into adetergent.

In EP-A-0,458,327, ureido peroxy carboxylic acids are described. InEP-A-0485928, the ureido percarboxylic acids are synthesised fromcarbamoyl lactams by cleavage of the N--C bonds of the lactam ring. Thecleavage reaction is carried out in concentrated sulphuric acid ormethane sulphonic acid, followed by addition of concentrated aqueoushydrogen peroxide.

Other nitrogen containing bleach activator compounds include phthalimidederivatives, for instance N-alkyl derivatives in which the alkyl groupincludes a percarboxylic group. Such compounds are described inEP-A-0,325,289 and EP-A-0,325,288, as well as EP-A-0,166,041. Othernitrogen containing derivatives include isatoic anhydride derivativessuch as disclosed in EP-A-0,332,050. Other cyclic nitrogen containingactivators are the 2-substituted benzoxazine-4-ones such as described inEP-A-0,332,294.

Compounds falling within the scope of formula I herein are knowncompounds. For instance in U.S. Pat. No. 4617417, compounds of theformula I in which R² is H and A is O and in which the group at theposition represented by L is alkoxy are described as intermediates formaking diones which are known as cardiotonic agents. In EP-A-0561758,similar compounds are described as intermediates which are saponifiedand subsequently have the alkoxy carbonyl protecting group removed toform chiral β-amino acids. In GB-A-0959204, similar compounds areintermediates in the synthesis of herbicides which are carbamic estersin which the group represented by L in formula I is an alkyl aminogroup. In GB-A-1472154, similar compounds are hydrogenated andsubsequently have a benzyloxycarbonyl protecting group for the aminefunctionality removed, in the synthesis of pyroglutamyl compounds whichhave anti-depressive activity. In U.S. Pat. No. 2855436, similarcompounds in which R¹ is 1,2-phenylene are cyclised to form a condensedring system including an isatoic anhydride structure, which aresubsequently used as synthetic intermediates for making insecticides. InEP-A-0144290, Ω-amino carboxylic acids are first of all treated toprotect the amine group using benzyloxycarbonyl group and subsequentlyesterified and used as an intermediate in the formulation of apolypeptide having anti-hypertensive properties.

Compounds of the formula I as herein defined in which the grouprepresented by L is an alkoxy group, and which X is either O or S and Ais O or S themselves have herbicidal properties. Such properties arealso described in GB-A-1465451. In GB-A-2231871, such compounds are saidto be useful in the thickening or solidification of oily liquids, forexample in cosmetics, pharmacy and paint industry. In U.S. Pat. No.3078301, such compounds are used as plasticisers for polyvinyl resins.

There is still a need for improved bleach activator compounds which givegood bleaching at low temperatures, but which have minimal dye damageand fabric damage properties and bleach a wide range of stains.

A new composition according to the present invention, which is ofparticular use as a bleach composition, comprises a peroxygen bleachprecursor and a compound of the formula I: ##STR2## in which X is O orS; one of E and G is --A-- and the other is --N(R²)--;

A is --O-- or --S--;

R¹ is a C₁₋₅₀ alkylene group (including cyclo alkylene), optionallyinterrupted by an arylene group and/or by one or more ether, ester,anhydride, thioether, secondary or tertiary amine, amide or imidelinkage, an arylene group or an alkarylene group;

R², is selected from H, alkyl, aralkyl, alkaryl and aryl;

R³ is alkyl, alkaryl, aralkyl or aryl, or, when E is --N(R²)--, H;

in which R² and R³ can be joined so as to form a heterocyclic ring withthe atoms to which they are attached, and/or in which R¹ can be joinedwith R² or R³ ; and

L is a leaving group which may optionally be joined to any of R¹, R² andR³.

In the general formula I when E is --N(R²)--, R³ is selected from H,alkyl, aralkyl, alkaryl and aryl.

In the general formula I, X is preferably O.

In a preferred aspect, the molecular weight of the compound of formula Iis less than 1000.

In one preferred aspect of the present invention, A is --O--. PreferablyE is --A--; so that G is --N(R²)--.

R¹ preferably includes 1-12 carbon atoms. Preferred examples areunsubstituted C₁₋₆ alkylene and 1,2-arylene groups, preferablyunsubstituted arylene.

Alkyl groups in any of R² and R³ are preferably lower alkyl, forinstance C₁₋₈.g-alkyl, more preferably C₁₋₆ -alkyl. Preferred examplesare C₁₋₂ -alkyl. R² may be hydrogen.

In one preferred aspect of the invention R³ and R² are joined to make a5 or 6 membered ring with the moiety ##STR3## For instance, R² and R³together are unsubstituted C₂ -alkylene.

Any alkyl groups (including alkylene) may include unsaturated bonds, forinstance ethylenically unsaturated bonds. Thus, where the contextpermits, alkyl includes alkenyl and alkynyl groups. It is preferred thatalkyl groups do not include unsaturated carbon--carbon bonds. Any alkylor aryl groups in any of the groups R¹, R² and R³ may be substituted,for instance with groups to improve the water solubility of thecompound, provided these do not detract from the performance of theactivator. Substituents can include hydroxyl, ═N--R⁵, in which R⁵ isselected from any of the groups represented by R² and is preferablylower alkyl, as well as amine, acyl, acyloxy, alkoxy, aryl, aroyl,aryloxy, aroyloxy, halogen, amido, and imido groups.

Alkyl and alkylene groups may be branched or straight substitutednitrogen atoms or carbonyl groups.

The leaving group L is preferably a compound the conjugate acid of whichhas a pK_(a), in the range 4-13, preferably 7-11, most preferably 8-11.Preferred leaving groups are: ##STR4## R⁶, R⁷, R⁸ and R⁹ are eachselected from H, alkyl (preferably lower alkyl, most preferably methyl)and/or and aryl and may be joined to other groups in the moiety L or inany of R¹ to R⁴ to form a cyclic activating compound;

R¹⁰ is an alkyl chain containing from 1 to 8 carbon atoms; R¹¹ is loweralkylene, preferably C₁ to C₄ -alkylene

Z is H or a solubilising group.

The preferred solubilising groups Z are --SO₃ ⁻ M⁺, --COO⁻ M⁺, --SO₄ ⁻M⁺, ##STR5## and (and most preferably --SO₃ ⁻ M⁺ and --COO⁻ M⁺) whereinR⁴ is an alkyl chain containing from 1 to 4 carbon atoms, M is a cation,with sodium and potassium being most preferred, and X is a halide,hydroxide, methylsulfate or acetate anion.

L is preferably OR¹⁰, OPh or ##STR6## where R⁷ is lower alkyl or islower alkylene such that together with R¹, R⁷ forms a trivalent loweralkyl group (i.e. is joined to a lower alkylene group R¹) and R¹⁰ islower, preferably C₁₋₆ -alkyl.

The present invention provides further a process in which a compound ofthe formula I is contacted in aqueous solution with a peroxygen bleachprecursor to form the compound of the formula II ##STR7##

in which R¹, E, G. X and R³ have the meanings mentioned above inconnection with the activator compound or R² or R³ is R⁴ R¹³ H and R¹³corresponds to the group L defined above wherein L is joined to R² or R³as the case may be and R⁴ is alkylene

or arylene, or R¹ is ##STR8## where R¹² is trifunctional alkyl or aryland R¹³ corresponds to the group L defined above when L is joined to R¹(i.e. as derived from an activator compound of the formula I in which Lis joined to one of R¹, R² and R³), or its anionic form (i.e. in asalt).

The peroxygen bleach precursor may be hydrogen peroxide or may be aninorganic persalt, for instance a percarbonate, perborate, persulfate,alternatively it may be an organic peroxygen compound such as benzoylperoxide, or other percarboxylic acid compound.

The process is generally carried out in conditions generally applicableto bleaching conditions, for instance used in laundry detergent liquorsor cleaners used in a domestic environment. The process is generallycarried out at an alkaline pH, for instance in the range 9-13, but mayalso be carried out at an acidic pH or a pH in the range from acidic topK_(a) of the percarboxylic acid of the formula II.

Some compounds of the formula II are novel compounds. The presentinvention also covers those compounds. In a preferred class, R¹ is analkylene group. Preferably E is A.

Instead of generating a percarboxylic acid in situ in the bleachingliquor, the new percarboxylic acids or salts thereof, may be dissolveddirectly into an aqueous solution to form the bleaching liquor.Magnesium salts of the percarboxylic acid of the novel compounds offormula II are particularly useful as they are relatively storagestable. The present invention covers compositions containing thosesalts.

Where an activator of the formula I is included in a storage stablecomposition, as in the preferred composition, the composition preferablyalso contains a peroxygen bleach precursor, such as are described above.

The compositions may further contain components conventionally used inbleaching compositions, for instance pH-adjusters, builders,surfactants/wetting agents which may be cationic, anionic, amphoteric ornonionic, as well as disinfectants, biocides, slimicides, enzymes,inhibitors or radical scavengers, abrasives, colouring agents, soilsuspending agents, optical brightening agents, fabric softeners, etc.The activator of the formula I may be used in conjunction withco-activators such as tetraacetyl ethylene diamine (TAED), tetraacetylglycol uril (TAGU) or alkanoyloxybenzene sulphonates, or with preformedperacids, such as PAP (N-phthalimido perhexanoic acid), or withtransition metal catalysts or organic catalysts such as enzymes or anyother activating moiety. The peracid of the invention may be used as themagnesium salt. The peracid, when formed in situ from activator andperoxygen source, may react with further activator to form a diacylperoxide which is an oxidising species.

The compositions may be in any suitable form, such as powder, granular,tablet, cake, or liquid, which may be aqueous or non-aqueous based. Whenthe compositions are in the preferred granular form, the activator andperoxygen source are preferably contained in separate granulecomponents. These may, in turn, be produced by known granulationtechniques, for instance techniques such as are described inEP-A-0,238,341, EP-A-0,299,599, EP-A-0,482,806, and preferably comprisebinders, for instance meltable binders such as nonionic surfactants, orstarch or cellulose-based binders such as carboxy methyl cellulose, orsynthetic polymer binders such as acrylate ester binders. The granulesmay be produced. by the usual techniques of agglomeration, granulation,extrusion of a dispersion in a molten binder or of a moistened powderblend, optionally followed by spheronisation and/or coating foradditional storage stability.

The bleach activator composition and preferably the granules containingbleach activator preferably contains a bleach stabiliser, that is asequestrant, such as a poly(methylene phosphonic acid) sequestrant or apolycarboxylic acid sequestrant. Suitable sequestrants are in particularalkylene polyamine poly(methylene phosphonic acids) and their salts.

The activator granules may contain other agents to improve dissolutionor dispersion, for instance effervescent compounds, swelling agents,water soluble salts etc.

The invention is illustrated in the following examples:

EXAMPLE 1 Preparation of N-Benzyloxycarbonyl Aspartic Anhydride(Compound A) ##STR9##

The above illustrated starting compound which is commercially availableN-CBZ aspartic acid (205.7 g, 0.77 mol) was added to acetic anhydride(300 ml). This mixture was stirred at 75° C. for 4 hours. The excessacetic anhydride and acetic acid byproduct were distilled from themixture under reduced pressure and the residue was recrystallised fromhot dichloromethane. The product was collected by filtration, washedwith hexane and dried at ambient temperature under reduced pressure togive a white fluffy solid.

Yield=137.7 g (72%)

Infra-red spectrum and nmr spectrum were consistent with the requiredstructure, compound A, in which R¹ is methylene and is joined to a groupL which is a group ##STR10## in which R⁷ is methylene, E is --O--, G is--N(R²)--in which R² is H, R³ is benzyl and X is O.

EXAMPLE 2 Preparation of Phenyl N-Ethoxycarbonyl Sarcosinate (CompoundB) ##STR11##

A stirring mixture of ethyl sarcosinate hydrochloride (200 g, 1.30 mol)(which is commercially available), triethylamine (303.4 g 3.00 mol) andacetonitrile (900 ml) was cooled using an ice/water bath. Ethylchloroformate (170 g, 1.57 mol) was dissolved in acetonitrile (200 ml)and added in portions to the reaction mixture. Once the addition wascomplete, the resulting mixture was held at reflux for four hours. Oncethe reaction mixture had cooled to ambient temperature, it was filteredand then the bulk of the acetonitrile was removed by distillation underreduced pressure. The residue was taken up in ether (600 ml) and washedwith aqueous hydrochlorid acid (5%, 1×400 ml), water (1-400 ml) aqueoussodium hydroxide solution (5%, 1-400 ml) and water (1-400 ml). Theethereal solution was dried over anhydrous sodium sulphate and thenfiltered. The ether was removed by distillation under reduced pressureto give the product as an orange liquid.

Yield=191 g (78%)

ii) Preparation of N-ethoxycarbonyl sarcosine ##STR12##

Ethyl N-ethoxycarbonyl sarcosinate (191 g, 1.01 mol) was dissolved inmethanol (400 ml) and sodium hydroxide (45.4 g, 1.14 mol) was dissolvedin deionized water. The two solutions were mixed together and stirredfor four hours. The reaction liquor was concentrated by distillation ofa methanol/ethanol mixture under reduced pressure. Deionized water (250ml) was added to the residue. This aqueous solution was washed withether (2×200 ml) and then acidified with hydrochloric acid to pH 1. Theproduct was extracted with ether (3-200 ml) and the extracts werecombined and dried over anhydrous magnesium sulphate. The etherealsolution was filtered and the ether was removed by distillation underreduced pressure to give the crude product as a yellow liquid. Thisliquid was distilled at 5 mbar to give the product as a clear colourlessoil, bp 135°-140° C.

Yield=138 g (84%)

Infra-red spectrum and nmr spectrum were consistent with the requiredstructure.

iii) Preparation of phenyl N-ethoxycarbonyl sarcosinate ##STR13##

N-ethoxycarbonyl sarcosine (60.0 g, 0.372 mol) and acetic anhydride (200ml) were heated together at 80° C. for two hours. The excess aceticanhydride and acetic acid byproduct were removed by distillation underreduced pressure to give the intermediate anhydride. Phenol (20.0 g,0.213 mol) was added and the mixture was heated at 80° C. for ninehours. The reaction mixture was dissolved in ether (150 ml) and washedwith aqueous sodium hydroxide solution (5%, 2×200 ml), water (1×100 ml)and aqueous sodium chloride soution (10%, 1×100 ml). The etherealsolution was dried over anhydrous sodium sulphate and then filtered. Theether was removed by distillation under reduced pressure to give thecrude product as a pale yellow syrup. This syrup was distilled at 1 mbarto give the product as a clear colourless oil, bp 104° C.

Yield=28.7 g (65%)

HPLC purity=98 area %

Infra-red spectrum and nmr spectrum were consistent with the requiredstructure, compound B, in which L is OPh, R¹ is methylene, G is--N(R²)-- in which R² is methyl, E is --O--, X is O and R¹ is ethyl.

EXAMPLES 3 and 4 Wash tests

The bleach activators prepared in examples 1 and 2 were tested forwashing performance, comparisons being made using: (i) a blankincorporating no bleach activator and (ii) a comparative known bleachactivator.

Swatches of 100% cotton 12 cm×12 cm were stained using the stains listedbelow:

    ______________________________________                                        WIL Tea    Tea prepared by Warwick International Group                                   Limited                                                            Red wine   Red wine stains                                                    BC1        Tea stains with clay                                               BC2        Coffee stains                                                      BC3        Tea stains                                                         BC4        Curry stains                                                       BC5        Red beet stains                                                    AS4        Chlorophyll in vegetable oil stains                                ______________________________________                                    

These stains are useful to give an indication of the bleaching power offormulations incorporating bleach activator. AS4 is particularly good atindicating bleaching performance on oily stains.

Wash tests were carried out under conditions typical of European laundrywashing conditions. Wash tests were carried out at 40° C. using coldfill Wascator FOM 71 MP machines, programmed to BS 4923 (HLCC) washprogrammes.

Formulations incorporating the activator for testing were preparedcontaining 22.4 g PBS4 (sodium perborate tetrahydrate), 124.5 g IECstandard base detergent and a weight of activator calculated to give thesame moles peracid release as 2% by weight TAED assuming 1 mole ofactivator releases 1 mole of peracid and taking into account the purityof the activator compound synthesised as determined by HPLC.Formulations were dosed at 7.5 g/l wash water via the dispensing drawerof the machines.

During the wash tests the swatches were tagged to 2.5 kg polyesterbacking cloth, using plastic tags. After washing the swatches wereremoved and ironed dry prior to reading reflectance measurements toassess stain removal. Stain removal was assessed as a percentagebrightness and calculated using the equation. ##EQU1## where RA is thereflectance of the washed swatch, RB is the reflectance of the unwashedswatch and RS is the reflectance of an unstained swatch. Reflectance wasmeasured with U.V. at 420 nm using a Spectroflash 500 Spectrophotometermachine.

Due to variations in swatch make up, all evaluations were run comparedto a TAED tetracetylethylenediamine standard, as well as a blankincorporating no activator.

                  TABLE                                                           ______________________________________                                        EUROPEAN WASHES AT 40°                                                 STAIN REMOVAL (% z - BRIGHTNESS:SPECTRAFLASH                                           FORMULATION                                                          SWATCH     Blank  Ex3        Ex4  TAED Std                                    ______________________________________                                        Red Wine   36.0   37.6       39.5 42.2                                        WIL Tea    21.2   29.2       30.5 31.8                                        BC1        5.4    5.1        8.0  7.6                                         BC2        7.4    5.8        12.0 9.4                                         BC3        8.8    9.0        14.2 14.0                                        BC4        8.9    6.9        11.1 8.5                                         BC5        7.6    7.3        10.0 10.2                                        AS4        11.5   9.6        10.4 11.8                                        ______________________________________                                        FORMULATIONS:                                                                 1.  Blank:    22.4 g PBS4, 124.5 g IEC Base.                                  2.  TAED Std: 3.0 Uncoated TAED, 22.4 g PBS4, 124.5 g                                       IEC Base.                                                       3.  EX3:      6.560 g Compound A, 22.4 g PBS4,                                              124.5 g IEC Base.                                               4.  Ex4:      6.372 g Compound B, 22.4 g PBS4,                                              124.5 g IEC Base.                                           

Wash test results are given in the Table, from which it can be seen thatactivators according to the invention boost the perborate bleaching andin some cases outperform TAED which is itself a very good bleachactivator.

We claim:
 1. A composition comprising a peroxygen bleach precursor and acompound of formula I:

    R.sup.3 --E--C(X)--G--R.sup.1 --C(O)--L                    (I)

in which X is O or S; one of E and G is --A-- and the other is--N(R²)--; A is --O-- or --S--; R¹ is selected from the group consistingof arylene, aliphatic hydrocarbon-arylene and C₁₋₅₀ divalent aliphaticor cycloaliphatic hydrocarbon which is optionally interrupted by atleast one group selected from the group consisting of arylene, ether,ester, anhydride, thioether, secondary or tertiary amine, amide andimide linkage; R² is selected from the group consisting of H, aliphatichydrocarbon, aliphatic hydrocarbon-aryl, aryl-aliphatic hydrocarbon andaryl; R³ is selected from the group consisting of aliphatic hydrocarbon,aliphatic hydrocarbon-, aryl-aliphatic hydrocarbon or aryl, or, when Eis --N(R²)--, H; and L is a leaving group the coniugate acid of whichhas a pK_(a) of 4 to 13, optionally connected to at least one of R¹, R²and R³.
 2. A composition according to claim 1 in which X is O.
 3. Acomposition according to claim 2 in which A is --O--.
 4. A compositionaccording to claim 1 in which A is --O--.
 5. A composition according toclaim 1 in which R² and R³ are alkyl.
 6. A composition according toclaim 5 in which R² and R³ are C₁₋₈ -alkyl.
 7. A composition accordingto claim 6 in which R² and R³ are C₁₋₂ -alkyl.
 8. A compositionaccording to claim 1 in which L is OR¹⁰, OPh or O--C(O)--R⁷ wherein R⁷is C₁₋₈ alkyl or is C₁₋₆ alkylene and is joined to R¹ and wherein R¹⁰ islower alkyl.
 9. A composition according to claim 8 in which R¹⁰ is C₁₋₆alkyl.
 10. A composition according to claim 1 in which the compound ofthe formula I has a molecular weight of less than
 1000. 11. Acomposition according to claim 1 in which the peroxygen bleach precursoris hydrogen peroxide or an inorganic persalt.
 12. A compositionaccording to claim 11 in which the peroxygen bleach precursor is sodiumperborate or sodium percarbonate.
 13. A composition according to claim 1which is a concentrate which is dilutable with water to provide ableaching liquor.
 14. A composition according to claim 8 in which R⁷ isjoined to R¹.
 15. A method in which a compound of formula I:

    R.sup.3 --E--C(X)--G--R.sup.1 --C(O)--L                    (I)

in which X is O or S; one of E and G is --A-- and the other is--N(R²)--; A is --O-- or --S--; R¹ is selected from the group consistingof arylene, aliphatic hydrocarbon-arylene and C₁₋₅₀ divalent aliphaticor cycloaliphatic hydrocarbon, which is optionally interrupted by atleast one group selected from the group consisting of arylene, ether,ester, anhydride, thioether, secondary or tertiary amine, amide andimide linkage; R² is selected from the group consisting of H, aliphatichydrocarbon, aliphatic hydrocarbon-aryl, aryl-aliphatic hydrocarbon andaryl; R³ is selected from the group consisting of aliphatic hydrocarbon,aliphatic hydrocarbon-aryl, aryl-aliphatic hydrocarbon or aryl, or, whenE is --N(R²)--, H; and L is a leaving group the conjugate acid of whichhas a pK_(a), of 4 to 13, optionally connected to at least one of R¹, R²and R³ is contacted in aqueous solution with a peroxygen bleach source.16. A method according to claim 15 in which X and A are O.
 17. A methodaccording to claim 15 in which R² and R³ are C₁₋₈ -alkyl.
 18. A methodaccording to claim 15 in which L is OR¹⁰, OPh or O--C(O)--R⁷ wherein R⁷is C₁₋₈ alkyl or is C₁₋₆ alkylene and is joined to R¹ and wherein R¹⁰ islower alkyl.
 19. A method according to claim 15 in which the compound ofthe formula I has a molecular weight of less than
 1000. 20. Apercarboxylic acid of the formula II or a salt thereof

    R.sup.3 --E--C(X)--G--R.sup.1 --C(O)--OOH                  (II)

in which X is O or S; one of E and G is --A-- and the other is--N(R²)--; A is --O-- or --S--; R¹ is selected from the group consistingof arylene, aliphatic hydrocarbon-arylene and C₁₋₅₀ divalent aliphaticor cycloaliphatic hydrocarbon, which is optionally interrupted by atleast one group selected from the group consisting of arylene, ether,ester, anhydride, thioether, secondary and tertiary amine, amide andimide linkages; R² is selected from the group consisting of H, aliphatichydrocarbon, aryl-aliphatic hydrocarbon, aliphatic hydrocarbon-aryl andaryl; R³ is selected from the group consisting of aliphatic hydrocarbon,aryl-aliphatic hydrocarbon, aliphatic hydrocarbon-aryl and aryl, or,when E is --N(R²)--, is H.
 21. A percarboxylic acid compound accordingto claim 20 in which R¹ is an alkylene group.
 22. A percarboxylic acidcompound according to claim 20 in which A is --O--.
 23. A compoundaccording to claim 20 in which X is O.
 24. A compound according to claim20 in which R² and R³ are alkyl.
 25. A compound according to claim 20 inwhich R² and R³ are C₁₋₈ -alkyl.
 26. A compound according to claim 20 inwhich R² and R³ are C₁₋₂ -alkyl.